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HomeMy WebLinkAboutBANK OF COLORADO - PDP - 16-03 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTIDRAINAGE CRITERIA MANUAL (V.3) ' 10.0 6.0 ' 4.0 2.0 ' 1.0 ' 0.60 m CU ' 0.40 E m 0.20 U _a t CU CU C7 m 0.10 iu 0.06 0.04 0.02 ' 0.01 0.02 STRUCTURAL BEST MANAGEMENT PRACTICES EXAMPLE: DWO = 4.5 ft WQCV = 2.1 acre-feet SOLUTION: Required Area per Row = 1.75 in? EQUATION: WQCV a= K 40 in which, K40=0.013DWQ+0.22DWQ -0.10 O� 74 Qr O� J� 0.04 0.06 0.10 0.20 0.40 0.60 1.0 2.0 4.0 6.0 Required Area per Row,a (in.2 ) FIGURE EDB-3 Water Quality Outlet Sizing: Dry Extended Detention Basin With a 40-Hour Drain Time of the Capture Volume ' 9-1-99 Urban Drainage and Flood Control District 5-43 STRUCTURAL BEST MANAGEMENT PRACTICES DRAINAGE CRITERIA MANUAL (V. 3) 0.50 0.45 0.40 0.35 m L 0.30 a m L m 0.25 m 3 > 0.20 U 3 0.15 0.10 0.05 0 00 Extended Detention Basin 40-hour Drain Time Constructed Wetland Basin 24-hour Drain Time 6-hr drain time a = 0.7 12-hr drain time a = 0.8 7Ai) 24-hr drain time a = 0.9 40-hr drain time a = 1.0 01*1 Retention Pond, Porous Pavement Detention and Porous Landscape Detention 12-hour Drain Time 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Total Imperviousness Ratio (i =1 Q/100) 0.8 0.9 1 FIGURE EDB-2 Water Quality Capture Volume (WQCV), 8dh Percentile Runoff Event S-42 9-1-99 Urban Drainage and Flood Control District No Text APPENDIX F FIGURES AND TABLES I [1 1 t 7 1 North Star Design, Inc. 700 Automation Drive, Unit I Windsor, CO 80550 EROSION CONTROL COST ESTIMATE LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design, Inc. DATE: 5/5/03 ITEM QUANTITY JUNIT COST/UNIT ITOTAL COST Silt Fence 950 LF $3 $2,850 Straw Bale Barrier 0 EA $150 $0 Gravel Inlet Filter 3 EA $150 $450 Construction Entrance 2 EA $550 $1,100 Subtotal Contingency (50%) Total $4,400 $2,200 $6,606 CITY RESEEDING COST Reseed/Mulch 1.4 ACRE $615 $861 Subtotal Contingency (50%) Total $861 $431 $1,292 EROSION CONTROL ESCROW AMOUNT $6,600 Page 3 EFFECTIVENESS EFFECTIVENESS CALCULATIONS PROJECT: Bank of Colorado at Lincoln & Lemay STANDARD FORM B COMPLETED BY: PPK DATE: 05-May-03 EROSION CONTROL C-FACTOR P-FACTOR METHOD VALUE VALUE COMMENT BARE SOIL 1.00 1.00 SMOOTH CONDITION ROUGHENED GROUND 1.00 0.90 SEDIMENTBASIN 1.00 0.50 ROADS/WALKS 0.01 1.00 GRAVEL FILTERS 1.00 0.80 PLACED AT INLETS SILT FENCE 1.00 0.50 STRAW MULCH 0.06 1.00 ESTABLISHED GRASS 0.08 1.00 STRAW BARRIERS 1.00 0.80 EFF = (I -C'P)s l 00 MAJOR SUB BASIN AREA EROSION CONTROL METHODS BASIN BASIN (Ac) 1 0.60 SILT FENCE 0.13 Ac. ROADS/WALKS 0.35 Ac. STRAW MULCH 0.12 Ac. ROUGHENED GROUND 0.00 Ac. ESTABLISHED GRASS 0.00 Ac. NET C-FACTOR 0.23 NET P-FACTOR 0.16 EFF = (1-C•P)• 100 = 96.2% 2 0.66 SILTFENCE 0.18 Ac. ROADS/WALKS 0.36 Ac. STRAW MULCH 0.12 Ac. ROUGHENED GROUND 0.00 Ac. ESTABLISHED GRASS 0.00 Ac. NET C-FACTOR 0.29 NET P-FACTOR 0.16 EFF = (I-C'P)•100 = 95.4% 6 0.16 SILT FENCE 0.09 Ac. ROADS/WALKS 0.04 Ac. STRAW MULCH 0.03 Ac. ROUGHENED GROUND 0.00 Ac. ESTABLISHED GRASS 0.00 Ac. NET C-FACTOR 0.58 NET P-FACTOR 0.16 EFF = (I -C•P)• 100 = 90.8% TOTAL AREA = 1.42 TOTAL EFF = 95.2% REQUIRED PS = 70.9% ac _ (94.0%'29.77 ac. + ., +99.6%*0.40 ac)/l .14 ac ' Page 2 M RAINFALL PERFORMANCE RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: Bank of Colorado at Lincoln & Lemay STANDARD FORM A COMPLETED BY: PPK DATE: 05-May-03 DEVELOPED ERODIBILITY Asb Lsb Ssb Al * Li Ai * Si Lb Sb PS SUBBASIN(s) ZONE (AC) (Fr) (%) (FT) 1 MODERATE 0.60 50 0.6 30.0 0.4 2 MODERATE 0.66 100 0.7 66.0 0.5 3 MODERATE 0.16 120 0.5 19.2 0.1 Total 1 1.42 1 1 1 115.20 1 0.90 1 81.1 1 0.6 70.9% Asb = Sub -basin area Lsb = Sub -basin flow path length Ssb = Sub -basin slope Lb = Average flow path length = sum(Ai Li)/sum(Ai) Sb = Average slope = sum(Ai Si)/Sum (Ai) PS is taken from Table 8-a (Table 5.1, Erosion Control Reference Manual) by interpolation. An Erosion Control Plan will be developed to contain 70.9% of the rainfall sedimentation that would normally flow off a bare ground site during a 10-year, or less, precipitation event. Page 1 I 1 0 1 n APPENDIX E EROSION CONTROL CALCULATIONS E Emergency Overflow Spillway Sizing (Ultimate Condition) LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design DATE: 5/5/03 Equation for flow over weir _ toof berm Q = CLH31 it where C = weir coefficient = 3.1 4 _ spill elevation H = overflow height �— L = length of the weir 0 100 yr WSEL The pond has a spill elevation 0.0 ft above the maximum water surface elevation in the pond Spillways will be designed with 0.5 ft flow depth, thus H = 0.5 ft Size the spillway assuming that the pond outlet is completely clogged. South Pond Qloo = 1.20 cfs Spill elev = 4939.65 ft Min top of berm elev: 4940.65 Weir length required: L = 1.1 It Use L = 10 ft v = 0.17 ft/s 2 times the 100 year release 100 yr WSEL = 4939.65 ft FINAL Pond.xls ' PROPOSED DETENTION POND Detention Pond Outlet Sizing ' (100 yr event - Ultimate) LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design, Inc. ' DATE: 5/5/03 Submerged Orifice Outlet: ' release rate is described by the orifice equation, Qo = COA, sgrt( 2g(h-E,)) where Qo = orifice outflow (cfs) ' Co = orifice discharge coefficient g = gravitational acceleration = 32.2 ft/s Ao = effective area of the orifice (ft`) ' Eo = greater of geometric center elevation of the orifice or d/s HGL (ft) h = water surface elevation (ft) Qmax = 0.60 cfs outlet pipe dia = D = 18.0 in ' Invert elev. = 4935.00 ft Eo = 4935.14 ft h = 4939.65 ft - 100 yr WSEL Co = 0.6 solve for effective area of orifice using the orifice equation 0.059 ft` 8.5 in` orifice dia. = d = 3.28 in Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering) d / D = 0.18 kinematic viscosity, v = 1.22E-05 ft2/s Reynolds no. = Red = 4Q/(pdv) = 2.29E+05 Co = (K in figure) = 0.6 check Use d = 3.3 in A. = 0.059 ff` _ 00 = 0.61 cfs 1 8.55 in ' FINAL Pond.xls PROPOSED DETENTION POND STAGE - STORAGE TABLE (100-YEAR- ULTIMATE) LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design, Inc. DATE: 5/5/03 100 yr Detention Volume Required = Water Quality Capture Volume Required = Total 100 yr Volume Required = SOUTH POND n� 100 year HWEL 0.305 0.033 0.338 Stage (ft) Surface Area (ft) Incremental Storage (ac-ft) Total Storage (ac-ft) 4935 0 0 0 4936 2276 0.017 0.02 4936.30 2536 0.017 0.034 4937 3143 0.062 0.08 4938 4096 0.083 0.16 4939 4914 0.103 0.27 4939.65 5373 0.077 0.342 4940 5620 0.121 0.39 4941.00 11641 0.194 0.58 LOCATION: PROJECT NO: COMPUTATIONS BY SUBMITTED BY: DATE: PROPOSED RETENTION POND STAGE - STORAGE TABLE (100-YEAR- INTERIM) Bank of Colorado at Lincoln & Lemay 170-01 PPK North Star Design, Inc. 5/5/03 100 yr Detention Volume Required = 0.305 •2 Total 100 yr Retention Volume Required = 0.610 SOUTH POND 100 year HWEL NORTH POND 100 year HWEL Stage (ft) Surface Area (ft`) Incremental Storage (ac-ft) Total Storage (ac-ft) 4935 0 0 0 4936 2276 0.017 0.02 4937 3143 0.062 0.08 4938 4096 0.083 0.16 4939 4914 0.103 0.27 4939.95 5585 0.114 0.380 4940 5620 0.121 0.39 4941.00 11641 0.194 0.58 Stage (ft) Surface Area W) Incremental Storage (ac-ft) Total Storage (ac-ft) 4936.3 0 0.000 0.00 4937 1763 0.009 0.01 4938 2910 0.053 0.06 4939 4160 0.081 0.14 4939.95 4635 0.096 0.239 4940 4660 0.101 0.24 4941.00 12252 0.187 0.43 Total volume provided at elevation 4939.95 = 0.619 acre-ft I LOCATION: Bank of Colorado at Lincoln & Lemay ITEM: Water Quality Pond Sizing (Ultimate Only) COMPUTATIONS BY: ppk SUBMITTED BY: North Star Design, Inc From Urban Storm Drainage Criterial Manual Use 40-hour brim -full volume drain time for extended detention basin Water Quality Capture Volume = WQCV = (required storage/12)"(tributary drainage area) MAJOR BASIN Trib. area (ac) % Imperv. Req. Storage (in. of runoff) from Fig. EDB -2 WQCV (ac-ft) Dwo (ft) req. vol WQCV'1.2 (ac-ft) req. area/row (in 2/row) from Fig. EDB-3 POND #1 1.42 60.0 0.23 0.027 1.30 0.033 0.20 WQ outlet sizing for pond 1 From Figure 5, for 1/2 in. hole diameter Area of hole = 0.2 in' # of columns = 1 Area provided/row = 0.20 in Area Required/row = 0.20 in Use 1 columns of 112" diam holes MINIMUM DETENTION VOLUME REQUIRED ULTIMATE POND FAA METHOD (100-YEAR) LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design DATE: 5/5/03 Equations: A trib. To pond = 1.42 acre Qo = CIA C100 = 0.83 Vi = T C I A= T Qp Developed C A= 1.2 acre Vo =K QPo T QPo = 0.60 cfs S=Vi -Vo K= 1 Rainfall intensity from City of Fort Collins IDF Curve Storm Duration, T (min) Rainfall Intensity, i (in/hr) Qp (cfs) Vol. In Vi (ft) Vol. Out Vo (ft) Storage S (ft) Storage S (ac-ft) 5 9.95 11.7 3497 180 3317 0.08 10 7.72 9.0 5426 360 5066 0.12 20 5.60 6.6 7872 720 7152 0.16 30 4.52 5.3 9531 1080 8451 0.19 40 3.74 4.4 10515 1440 9075 0.21 50 3.23 3.8 11352 1800 9552 0.22 60 2.86 3.4 12062 2160 9902 0.227 70 2.46 2.9 12104 2520 9584 0.22 80 2.06 2.4 11584 2880 8704 0.20 90 1.90 2.2 12020 3240 8780 0.20 100 1.70 2.0 11949 3600 8349 0.19 110 1.57 1.8 12139 3960 8179 0.19 120 1.45 1.7 12230 4320 7910 0.18 130 1.36 1.6 12427 4680 7747 0.18 140 1.27 1.5 12498 5040 7458 0.17 150 1.19 1.4 12547 5400 7147 0.16 160 1.14 1.3 12821 5760 7061 0.16 170 1.09 1.3 13025 6120 6905 0.16 180 1.05 1.2 13285 6480 6805 0.16 Required Storage Volume: 9902 ft 0.227 acre-ft 2 year historic 1=1 M M 1=1 M M =11 M M 1=1 r =1 M M M M M 1=11 1=11 MINIMUM DETENTION VOLUME REQUIRED INTERIM POND FAA METHOD (100-YEAR) LOCATION: Bank of Colorado at Lincoln & Lemay PROJECT NO: 170-01 COMPUTATIONS BY: PPK SUBMITTED BY: North Star Design DATE: 5/5/03 Equations: A trib. To pond = 1.42 acre Qo = CIA C,00 = 0.83 Vi = T C I A= T Qo Developed C A= 1.2 acre Vo =K QPo T QPo = 0.00 cfs S=Vi -Vo K= 1 Rainfall intensity from City of Fort Collins IDF Curve Storm Duration, T (min) Rainfall Intensity, i (in/hr) Qo (cfs) Vol. In Vi (ft) Vol. Out Vo (ft) Storage S (ft) Storage S (ac-ft) 5 9.95 11.7 3497 0 3497 0.08 10 7.72 9.0 5426 0 5426 0.12 20 5.60 6.6 7872 0 7872 0.18 30 4.52 5.3 9531 0 9531 0.22 40 3.74 4.4 10515 0 10515 0.24 50 3.23 3.8 11352 0 11352 0.26 60 2.86 3.4 12062 0 12062 0.277 70 2.46 2.9 12104 0 12104 0.28 80 2.06 2.4 11584 0 11584 0.27 90 1.90 2.2 12020 0 12020 0.28 100 1.70 2.0 11949 0 11949 0.27 110 1.57 1.8 12139 0 12139 0.28 120 1.45 1.7 12230 0 12230 0.28 130 1.36 1.6 12427 0 12427 0.29 140 1.27 1.5 12498 0 12498 0.29 150 1.19 1.4 12547 0 12547 0.29 160 1.14 1.3 12821 0 12821 0.29 170 1.09 1.3 13025 0 13025 0.30 180 1.05 1.2 13285 0 13285 0.30 Required Storage Volume: 13285 ft 0.305 acre-ft Retention, no release I D 11 APPENDIX D POND SIZING CALCULATIONS E Label: Q1 Rim: 4,941.00 ft Sump: 4,935.50 ft 0� Profile Scenario: STORM 4 Label: P-1 Up. Invert: 4,936.30 ft Dn. Invert: 4,935.50 ft L: 190.00 ft Size: 15 inch S: 0.42 % Label: 1-1 Rim: 4,941.00 ft Sump: 4,936.30 ft 4,941.00 4,939.50 4,938.50 4,937.50 4,936.50 4,935.50 00 Elevation (ft) Title: Bank of Colorado Project Engineer: Patricia Kroetch e:\haestad\stmc\bankcol.stm North Star Design, Inc. StormCAD v4.1.1 [4.2014] 05/05/03 08:19:19 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Scenario: STORM 4 Combined Pipe\Node Report Label Upstream Downstream Length Section Constructed Discharge Average Upstream Hydraulic Upstream Downstream Hydraulic Downstream Node Node (ft) Size Slope O Velocity Invert Grade Ground Invert Grade Ground (%) (cfs) (ft/s) Elevation Line In Elevation Elevation Line Out Elevation (ft) (ft) (ft) (ft) (ft) (ft) P-1 1-1 0-1 190.00 15 inch 0.42 4.80 3.91 4,936.30 4,940.27 4,941.00 4,935.50 4,939.65 4,941.00 Title: Bank of Colorado Project Engineer: Patricia Kroetch e:\haestad\stmc\bankcol.stm North Star Design, Inc. Storm CAD v4.1.1 [4.2014) 05/05/03 08:18:57 PM m Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 lll� Ir r r r� r lllr Ir llllrF Ir r r r r ill. r r llllr lllr Profile Scenario: STORM 3 Label: P 3 Up. Invert: 4,936.18 ft Dn. Invert: 4,936.00 ft L: 17.65 ft Size: 10 inch S:1.02 % Label: P-2 Up. Invert: 4,936.57 ft Dn. Invert: 4,936.18 ft L: 39.35 ft Size: 10 inch S: 0.99 % Label: P 1 Up. Invert: 4,937.50 ft Dn. Invert: 4,936.57 ft L: 93.10 ft Size: 10 inch S:1.00 % Elevation (ft) Title: Bank of Colorado Project Engineer: Patricia Kroetch e:\haestad\stmc\bankco2.stm North Star Design, Inc. StormCAD v4.1.1 [4.2014] 05/05/03 08:20:20 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 Scenario: STORM 3 Combined Pipe\Node Report Label Upstream Downstream Length Section Constructed Discharge Average Upstream Hydraulic Upstream Downstream Hydraulic Downstream Node Node (ft) Size Slope Q Velocity Invert Grade Ground Invert Grade Ground (%) (cfs) (f /s) Elevation Line In Elevation Elevation Line Out Elevation (ft) (ft) (ft) (ft) (ft) (ft) P-1 1-1 1-2 93.10 10 inch 1.00 1.30 2.38 4,937.50 4,940.10 4,941.00 4,936.57 4,939.82 4,941.00 P-2 1-2 J-1 39.35 10 inch 0.99 1.30 2.38 4,936.57 4,939.82 4,941.00 4,936.18 4,939.70 4,941.00 P-3 I J-1 0-1 17.65 10 inch 1.02 1.30 2.38 4,936.18 4,939.70 4,941.00 4,936.00 4,939.65 4,941.00 Title: Bank of Colorado Project Engineer: Patricia Kroetch e:\haestad\stmc\bankco2.stm North Star Design, Inc. StormCAD v4.1.1 [4.2014] 05/05/03 08:19:51 PM Q Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1 I � I I I C 1 1 APPENDIX C HYDRAULIC CALCULATIONS C IM 1=1 Mr r North Star Design, Inc. 700 Automation Drive, Unit 1 Windsor, CO 80550 RATIONAL METHOD PEAK RUNOFF (NEW IDF CURVE) (100-YEAR) LOCATION: Bank of Colorado PROJECT NO: 170-01 COMPUTATIONS BY: ppk DATE: 5/5/03 100-yr storm, Cf = 1.25 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Des. Point Area Design. A (ac) C Cf is (min) i (new) (in/hr) Q (100) (cfs) from Design Point Q (100) (cfs) 0(100)tot (cfs) 1 1 0.60 0.80 5.0 9.95 4.8 4.8 2 2 0.66 0.85 5.0 9.95 5.5 5.5 3 1 3 0.16 0.84 5.0 9.95 1.3 1 1.3 2 Total Developed 1.42 0.83 5.0 9.95 11.7 11.7 Q=CiA Q = peak discharge (cfs) C = runoff coefficient I = rainfall intensity (in/hr) from IDF curve A = drainage area (acres) NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis) FINAL Flow.xls 0100 North Star Design, Inc. 700 Automation Drive, Unit 1 Windsor, CO 80550 RATIONAL METHOD PEAK RUNOFF (NEW IDF CURVE) (10-YEAR) LOCATION: Bank of Colorado PROJECT NO: 170-01 COMPUTATIONS BY: ppk DATE: 5/5/03 10-yrstorm, Cf 1.00 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Point Tributary Sub -basin A (ac) C Cf tc (min) I (new) (in/hr) Q (10) (cfs) from Design Point Q (10) ids) Q(10)tot (cfs) 1 1 0.60 0.64 6.5 4.44 1.7 1.7 2 2 0.66 0.68 5.0 4.87 2.2 2.2 3 1 3 0.16 0.67 5.0 4.87 1 0.5 0.5 2 Total Developed 1.42 0.66 5.0 4.87 4.6 4.6 Q=CfCIA Q = peak discharge (cfs) C = runoff coefficient Cf = frequency adjustment factor I = rainfall intensity (in/hr) from IDF curve A = drainage area (acres) NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis) FINAL Flow.xls Q10 M M r M M M M M M M M M M M M M M M M North Star Design, Inc. 700 Automation Drive, Unit I Windsor, CO 80550 RATIONAL METHOD PEAK RUNOFF (NEW IDF CURVE) (2-YEAR) LOCATION: Bank of Colorado PROJECT NO: 170-01 COMPUTATIONS BY: ppk DATE: 5/5/03 2-yr storm, Cf = 1.00 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Point Tributary Sub -basin A (ac) C Cf tc (min) i (new) (inRrr) Q (10) (cfs) from Design Point Q (10) (cfs) Q(10)tot (cfs) 1 1 0.60 0.64 6.5 2.60 1.0 1.0 2 2 0.66 0.68 5.0 2.85 1.3 1.3 3 3 0.16 0.67 5.0 2.85 0.3 1 1 0.3 2 Total Developed 1.42 0.66 5.0 2.50 2.3 2.3 2 Total historic 1.42 0.20 11.0 2.13 0.6 0.6 Allowable detention release Q=CrCiA Q = peak discharge (cfs) C = runoff coefficient Cf = frequency adjustment factor I = rainfall intensity (in/hr) from IDF curve A = drainage area (acres) NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis) FINAL Flow.xls 02 North Star Design, Inc. 700 Automation Drive, Unit I Windsor, CO 80550 LOCATION: PROJECT NO: COMPUTATIONS BY: DATE: 100-yr storm Bank of Colorado 170-01 ppk 5/5/03 Cf = 1.25 STANDARD FORM SF-2 TIME OF CONCENTRATION -100 YR SUB -BASIN DATA INITIAL /OVERLAND TIME III) TRAVEL TIME I GUTTER OR CHANNEL FLOW (tt) to CHECK (URBANIZED BASIN) FINAL to REMARKS DESIGN POINT SUBBASIN(s) (1) Area (ac) (2) C (3) C'Cf Length (ft) (4) Slope (%) (5) ti (min) (6) Length 00 (7) Slope (%) (8) n Manning rough. Vel. (fVs) (9) tt (min) (10) to t1+tt (11) Total 00 (12) tc=(1/180)+10 (min) (13) (min) (14) 1 1 0.60 0.64 0.80 60 1.2 3.9 50 0.60 0.016 1.6 0.54 4.4 110 10.6 5.0 2 2 0.66 0.68 0.85 28 1.2 2.3 100 0.70 0.016 1.7 0.99 3.3 128 10.7 5.0 3 3 0.161 0.67 0.84 20 6.0 1.2 120 0.50 0.016 1.4 1.41 2.6 140 10.8 5.0 2 Total Developed 1.42 0.66 0.83 28 1.2 2.5 100 0.70 0.016 1.7 0.99 3.4 128 10.7 5.0 2 Total historic 1.42 0.20 0.25 175 2.0 16.1 0 1.001 0.0161 2.0 0.00 16.1 175 11.0 11.0 EQUATIONS: tc=ti+tt ti=[1.87(1.1-CC1)Lo'sI/S1r' It = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual) final tc = minimum of ti + tt and urbanized basin check min. tc = 5 min. due to limits of OF curves FINAL Flow.xls TOC-100 M = i r = = = = M = = = M = M North Star Design, Inc. 700 Automation Drive, Unit I Windsor, CO 80550 LOCATION: PROJECT NO: COMPUTATIONS BY: DATE: 10-yr storm Bank of Colorado 170-01 ppk 5/5/03 Cf = 1.00 STANDARD FORM SF-2 TIME OF CONCENTRATION -10 YEAR SUB -BASIN DATA INITIAL /OVERLAND TIME IV) TRAVEL TIME / GUTTER OR CHANNEL FLOW (tt) to CHECK (URBANIZED BASIN) FINAL to REMARKS DESIGN POINT SUBBASIN(s) (1) Area (ac) (2) C (3) Length (ft) (4) Slope (%) (5) it (min) (6) Length (It) (7) Slope (%) (8) n Manning rough. Val. (ft/s) (9) It (min) (10) tc = ti+It (11) Total (ft) (12) tc=(1/180)+10 (min) (13) (min) (14) 1 1 0.60 0.64 60 1.2 6.0 50 0.60 0.016 1.6 0.54 6.5 110 10.6 6.5 2 2 0.66 0.66 28 1.2 3.8 100 0.70 0.016 1.7 0.99 4.8 128 10.7 5.0 3 3 0.16 0.67 20 6.0 1.9 120 0.50 0.016 1.4 1.41 3.3 140 10.8 5.0 2 Total Developed 1.42 0.66 28 1.2 3.9 100 0.70 0.016 1.7 0.99 4.9 128 10.7 5.0 2 Total historic 1.42 0.20 175 2.0 17.0 01 1.001 0.0161 2.0 0.00 17.0 175 11.0 11.0 EE- EQUATIONS: tc=ti+tt ti=[1.87(1.1-CCI)L"']/S113 tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual) final tc = minimum of ti + tt and urbanized basin check min. tc = 5 min, due to limits of IDF curves FINAL FlowAs TOC-10 North Star Design, Inc. 700 Automation Drive, Unit I Windsor, CO 80550 RUNOFF COEFFICIENTS & %IMPERVIOUS LOCATION: Bank of Colorado PROJECT NO: 170-01 COMPUTATIONS BY: ppk DATE: 5/5/03 Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria Recommended % Impervious from Urban Storm Drainage Criteria Manual Streets, parking lots (asphalt) Sidewalks (concrete) Roofs Lawns (Flat <2%, heavy soil) Runoff % coefficient Impervious C 0.95 100 0.95 96 0.95 90 0.20 0 SUBBASIN DESIGNATION TOTAL AREA (ac.) TOTAL AREA (sq.ft) ROOF AREA (sq.ft) PAVED AREA (sq.ft) SIDEWALK AREA (sq.ft) LANDSCAPE AREA (sq.ft) RUNOFF COEFF. (C) % Impervious REMARKS 1 0.60 26,300 400 16,092 0 10,808 0.64 59 2 0.66 28,600 2,535 13,529 2,100 10,436 0.68 62 3 0.16 6,860 2,535 0 1,780 2,545 0.67 58 Total Developed 1.42 61,760 5,470 28,621 3,880 23,789 0.66 60 Total historic 1.42 61,760 0 0 0 61,760 0.20 0 Equations - Calculated C coefficients & % Impervious are area weighted C=E(Ci Ai) /At Ci = runoff coefficient for specific area, Ai Ai = areas of surface with runoff coefficient of Ci In = number of different surfaces to consider At = total area over which C is applicable; the sum of all Al's FINAL Flow.xls Cval I [1 [1 1 11 I 1 1 APPENDIX B HYDROLOGIC COMPUTATIONS 12 No Text APPENDIX A VICINITY MAP I 11 I I A 1 7. REFERENCES 1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986. 2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated September 1999. 6 5.2 Specific Details To limit the amount of silt leaving the site several erosion control measures shall be implemented during construction. Straw bales will be used where appropriate, and the ' north, west and east boundaries shall have silt fence installed. A vehicle tracking pads shall be installed at the proposed connections to Lemay Avenue and Lincoln Avenue to control the mud being tracked onto the existing pavement. During overlot grading, disturbed areas are to be kept in a roughened condition and watered to reduce wind erosion. The retention pond will be used as a sediment trap during construction. ' 6. CONCLUSIONS 6.1 Compliance with Standards All computations that have been completed within this report are in compliance with the City of Fort Collins Erosion Control Reference Manual for Construction Sites and the Storm Drainage Design Criteria Manual. Requirements placed on the site related to the new rainfall criteria have been followed. No variances are required for the project. I6.2 Drainage Concept ' The proposed drainage concepts presented in this report and on the construction plans adequately provide for stormwater quality treatment of proposed impervious areas. ' Conveyance elements have been designed to pass required flows and to minimize future maintenance. If, at the time of construction, groundwater is encountered, a Colorado Department of ' Health Construction Dewatering Permit will be required. the ultimate condition, this retention pond will be filled in and an inlet will be installed on ' the north end of the pipe. Basin 2 includes the southeast portion of the site. Runoff from this basin will sheet flow ' and gutter flow into the south retention pond. This pond will be converted to a detention pond in the ultimate condition. In both the interim and the ultimate conditions, the pond will discharge into the existing 48" storm pipe south of this site. This pipe will convey the water east into a drainage swale along the north side of Lincoln Avenue and into Dry ' Creek. Basin 3 includes the southwest portion of the site. Runoff from this basin will be collected in a landscape drain and will be conveyed to the south retention pond. ' 4.3 Drainage Summary 1 Drainage facilities located outside of the right of way (including the ponds, proposed storm drain system and the pond outlet) will be maintained by the owners of the property. ' The storm system proposed in the right of way for Lemay Avenue will be owned and maintained by the City of Fort Collins. ' 5. EROSION CONTROL 5.1 General Concept ' This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort Collins Zone Maps. The potential exists for silt movement from the site and into the ' existing swale along Harmony Road. Potential also exists for tracking of mud onto existing streets which could then wash into existing storm systems. The required ' performance standard for the site is 70.9%. During construction and after final paving and building construction, this figure has been exceeded with the use of silt fence, straw bales and by using the retention pond as a sediment trap during construction. ' The erosion control escrow amount is $6,600. 1 4 Water quality volume was calculated using the method recommended in the "Urban Storm Drainage Criteria Manual' and will only be incorporated in the ultimate pond design. 3.4 Hydraulic Criteria ' All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Drainage Criteria and are included in Appendix C of this report. 4. DRAINAGE FACILITY DESIGN ' 4.1 General Concept The majority of the proposed development will be routed via sheet and gutter flow to the proposed retention ponds at the southeast corner of the site and in the northern portion of the site. In the interim condition, both ponds will act as retention ponds with a pipe connecting the two ponds. The ponds will be allowed to release downstream once the ' water in the roadside ditch downstream has dissipated. In the ultimate condition, the north pond will be filled in and the south pond will operate as a detention pond with a Icontrolled gravity release. Calculations for both conditions are included in the appendix. A storm pipe system is also being proposed for this development that collects water from the west side of Lemay Avenue and from the low point in Lemay Avenue north of this site. This water will be conveyed east to the existing storm system along the north side of Lincoln Avenue. 4.2 Specific Flow Routing A summary of the drainage patterns within each basin is provided in the following paragraphs. ' Basin 1 includes the improvements on the north half of the site. The north half of the proposed parking and a small portion of the building is within this basin. This basin sheet ' flows to the center of the basin and into the north proposed retention pond via curb openings. This pond discharges to the south pond in the southeast comer of the site. In ' 3 3. DRAINAGE DESIGN CRITERIA ' 3.1 Regulations This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage Design Criteria Manual" specifications. Where applicable, the criteria established in the ' "Urban Storm Drainage Criteria Manual' (UDFCD), 1984, developed by the Denver Regional Council of Governments, has been used. 1 I I I 3.2 Development Criteria Reference and Constraints The runoff from this site has been routed to conform to the requirements of the City Stormwater Department and Larimer County Engineering. In the interim condition, a retention pond is proposed that will provide 2 times the storage capacity required for the 2-hour 100-year storm event. Rex Burns at Larimer County Engineering has concerns about releasing any water from this development into the existing swale along the north side of Lincoln Avenue. The solution that was agreed to with Mr. Bums was to provide the storage as indicated and allow the pond to discharge downstream only after the water has dissipated in the downstream swale. This will be accomplished using a manual operated valve on the pond outfall pipe. In the ultimate condition, once improvements are made from this site to Dry Creek, the retention will be abandoned and detention will be provided in the south pond with a gravity release. It was assumed that the site would be allowed to release at the 2 year historic release rate from the site in this ultimate condition. 3.3 Hydrologic Criteria Runoff computations were prepared for the 10-year minor and 100-year major storm frequency utilizing the rational method. All hydrologic calculations associated with the basins are included in Appendix B of this report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub - basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub - basins and Design Points associated with this site. Detention and retention volume were determined using the FAA or Rational Method. 2 71 Ll I 1 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location ' The Bank of Colorado at Lincoln and Lemay is located in northeast Fort Collins. This project is located in the northeast quarter of Section 7, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. ' See the location map in Appendix A. ' The project is located at the northeast corner of Lincoln Avenue and Lemay Avenue. The project is bounded on the north by an existing house, on the east by undeveloped property, on the south by Lincoln Avenue and Buffalo Run Apartments and on the west by Lemay Avenue and undeveloped property. i 1 i 1 11 1 i 1 i 1.2 Description of Property The entire project consists of approximately 1.4 acres of land. One commercial bank building is proposed for the site with associated parking and drives. The land currently is very flat and slopes to the south and west at a range of approximately 0.5% to 1.0%. The flow from the site appears to flow east and south into the existing ditch along Lincoln. There is some ponding on site that currently evaporates or percolates into the ground. The site lies within the 100 year floodplain limits. The floodway does not encroach on the site. 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description The proposed development lies within the Poudre River Drainage Basin. 2.2 Sub -basin Description This site drains to the currently discharges into the swale along the north side of Lincoln Avenue. This drainage will be altered with the development of this site to flow to a retention pond which will release into the existing storm system along Lincoln Avenue. 1 I ITABLE OF CONTENTS TABLEOF CONTENTS............................................................................................................... m 1. GENERAL LOCATION AND DESCRIPTION ' 1.1 Location ........................................................................................................1 1.2 Description of Property ............................................................................................1 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description..........................................................................................I ' 2.2 Sub -Basin Description.............................................................................................1 3. DRAINAGE DESIGN CRITERIA ' 3.1 Regulations..............................................................................................................2 3.2 Development Criteria Reference and Constraints....................................................2 3.3 Hydrologic Criteria..................................................................................................2 3.4 Hydraulic Criteria ..................... ............................................................................... 3 4. DRAINAGE FACILITY DESIGN 4.1 General Concept.......................................................................................................3 ' 4.2 Specific Flow Routing.............................................................................................3 4.3 Drainage Summary ...................................................................................................4 ' 5. EROSION CONTROL 5.1 General Concept......................................................................................................4 5.2 Specific Details........................................................................................................5 6. CONCLUSIONS ' 6.1 Compliance with Standards....................................................................................5 6.2 Drainage Concept.....................................................................................................5 I7. REFERENCES....................................................................................................................6 IAPPENDICES A Vicinity Map B Hydrologic Computations C Hydraulic Calculations D Pond Sizing Calculations ' E Erosion Control Calculations F Figures and Tables iii �I I 1 North Star fl *am, design, inc. [1 ' May 5, 2003 Basil Hamdan ' City of Fort Collins Stormwater 700 Wood Street ' Fort Collins, CO 80522-0580 I 1 I RE: Final Drainage and Erosion Control Study for Bank of Colorado at Lincoln and Lemay Dear Basil, I am pleased to submit for your review and approval, this revised Final Drainage and Erosion Control Study for the Bank of Colorado at the northeast corner of Lincoln Avenue and Lemay Avenue. I certify that this report for the drainage design was prepared in accordance with the criteria in the City of Fort Collins Storm Drainage Manual. I appreciate your time and consideration in reviewing this submittal. Please call if you have any ' ii 700 Automation Drive, Unit I Windsor, Colorado 80550 ' 970-686-6939 Phone 9 870-686-1188 Fax 11 FINAL DRAINAGE AND EROSION CONTROL STUDY BANK OF COLORADO AT LINCOLN AND LEMAY 0 Prepared for: Bank of Colorado 1609 East Harmony Road Fort Collins, CO 80528 Prepared by: North Star Design 700 Automation Drive, Unit I Windsor, Colorado 80550 (970)686-6939 May 5, 2003 Job Number 170-01 0